At present, by a Computer Tomography (CT) technology, each part of the body may be diagnosed for disease. Take the lumbar intervertebral disc as an example, in order to obtain a clear intervertebral disc image, the whole lumbar is usually scanned at first to obtain a scout scan before the intervertebral disc is scanned axially. Then scanning parameters (including a scanning area, a scanning angle, etc.) are set on the scout scan for a single intervertebral disc, and axial scanning is performed based on the set scanning parameters. For a spiral scanning, an operator needs to set the posteriorly-reconstructed angle, area and the like so that the intervertebral disc can be determined from a three-dimensional image.
There exists a series of problems due to inappropriately setting parameters in the above manner that needs to preset scanning parameters or posteriorly-reconstructed parameters.
For example, for the axial scanning, after localization scanning, the operator needs to perform a very complicated inputting operation to set parameters for the axial scanning. These operations need relatively longer time, during which it is difficult for a patient to keep the posture in the localization scanning. Particularly for the elder and children, the position, angle, area and the like during the actual scanning will be very easily inconsistent with the set parameters due to posture change.
When setting parameters during the posterior reconstruction of the spiral scanning, there also exists a problem that a satisfactory image cannot be obtained due to the features such as the shape, position and the like of the part to be diagnosed or the mechanical reasons of the scanning machine itself.
Several kinds of conditions will be introduced as examples in the following in which the image obtained from the scanning cannot satisfy the clinical need.
For instance, when setting the position parameters, it is possible that due to a displacement of the position of the intervertebral disc on the Z-axis, the intervertebral disc image is not obtained just between two adjacent vertebras, and thus an image as shown in FIGS. 1a-1e are obtained. FIG. 13a shows a sagittal image of the intervertebral disc. Since the position parameters are not set appropriately, the axial scanning is performed at an upper part of the intervertebral disc so as to obtain slice images in FIGS. 13b-13e. The clinical diagnosis requires that the middle slices preferably only have soft tissue features and contain no vertebra tissue feature, while the slices at the two sides contain vertebra tissue features, which is advantageous in comparing a difference between the slice images in the middle and the slice images at the two sides to diagnose whether the intervertebral disc has pathological changes. However, the images as shown in FIGS. 13c and 13d, as the slice images in the middle, contain relatively more vertebra tissue features, but their contrast with the slice images at the two sides as shown in FIGS. 13b and 13e is relatively smaller, which is disadvantageous for the clinical diagnosis.
Moreover, as shown in FIGS. 14a-14e, since an inappropriate angle parameter is set in FIG. 14a, the middle slice images obtained in FIG. 14c contain a lower edge of an upside vertebra and the middle slice images obtained in FIG. 14d contain an upper edge of a downside vertebra, which is also disadvantageous in clinical comparison.
Furthermore, many patients' spines all have scoliosis pathological changes, as shown in FIG. 15, and there appears an angle caused by curvature of the spines at the coronal position. Since a scanning device at the utmost only supports a tilt to the head or to the foot, not supporting the tilt in other directions, a satisfactory image cannot be obtained in the axial scanning.
In addition, even if appropriate position and angle parameters are set, if the set slice thickness parameter is inappropriate, the clinical requirements still cannot be satisfied. For example, if an inappropriate thickness parameter is selected in the image as shown in FIG. 16a such that no slice images in FIGS. 16b-16e only contains soft tissue features, the requirements for the clinical diagnosis cannot be satisfied.
For the operator, it is very difficult to correct the image problems due to the above various conditions in the subsequent process, such that the image cannot satisfy the requirements of the clinical diagnosis. Therefore, the scan usually needs to be re-performed, which not only affects working efficiency, but also increases the patent's scanning dose.
Accordingly, there is a need to provide a novel system and method for generating a CT slice image, which is capable of accurately setting parameters so as to obtain a slice image satisfying the clinical requirements.